RFR: 8313424: JavaFX controls in the title bar (Preview) [v80]

[Michael Strauß]

> Implementation of [`StageStyle.EXTENDED`](https://gist.github.com/mstr2/0befc541ee7297b6db2865cc5e4dbd09).

Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:

  enable preview feature system properties for tests

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/1605/files
  - new: https://git.openjdk.org/jfx/pull/1605/files/06ce89a4..56868485

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=79
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=78-79

  Stats: 17 lines in 3 files changed: 2 ins; 14 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1605.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1605/head:pull/1605

PR: https://git.openjdk.org/jfx/pull/1605